Machine and method for making hardened-edged plaster board



A ril 8, 1924.

H. E. BROOKBY MACHINE AND METHOD FOR MAKING HARDENED EDGED PLASTER BOARDFiled Sept. 25 1922 2 Sheets-Sh eet 1 INVENTOR. H. E BROOKBY BY W MATTORNEYS.

April 8 1924." 1,489,693

.- H. E. BROOKBY MACHINE AND METHOD FOR MAKING HARDENED EDGED PL ASTERBOARD Filed Sept. 25, 1922 2 Sheets-Sheet 2 IN V EN TOR. H. 5200K BY BYWM A TTORNEYS.

Patent Apr. 1924.

isra'res PATENT OFFICE,"

HARRY E. BROOKIBY OF EVANSTO'N, ILLINOIS, ASSIGNOR T UNITED STATESGYPSUM COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF'ILLINOIS. v

MACHINE AND METHOD FOR MAKING HARDENED-EDGED PLASTER BOARD.

Application filed September 25,1922. Serial No. 590,362.

To all whom it may concern.

Be it known that I, HARRY E. BROOKBY,

i a citizen of the United States, residing at Evanston, in the county ofCook and State of Illinois, have invented new and useful Improvements inMachines and Methods for Making Hardened-Edged Plaster Board, of whichthe following is a specifications This invention relates to lmprovemenlsin the production of building materials and more particularly to amachine and method for making hardened edged plaster board.

Plaster board, comprising a body of plaster, with or without aggregates,having a fibrous'covering on the opposite flat sides, has been used formany years in the building trades as a substitute for wooden laths andas such was nailed to the studding of the building and finished with acomplete coat of wall plaster to produce a wall surface ready fordecorations, as is customary in dwellings and other buildings.

' plaster board at first was made by applying a layer of the body in aplastic state upon a bottom cover sheet and then applying a ,top coversheet which sheets bonded to the body as the plastic mass set. Whenplaster board of this type was made by mechanical means it was foundthat the body while plastic exuded at the edges and means were devisedfor maintaining the body within the cover sheets so as to have a fullsquared edge. At first this was'accomplished by trimming or sawing theboard a short distance from the original edges after it had been formedwhile the body was in a semiplastic state. This produced a full squarededge but was expensive and the body at the edges exposed so that thecovering sheets were liable to become detached and peel duringtransportation and the handling necessary before erection. I To overcomethese disadvantages, the bound edge laster board was developed in whichone s eet was wider than the other and was folded about the edges andattached on the opposite. side to the opposite sheet. This formed acovered edge .and insured its protection against disfigurement caused bythe body crumbling, cracking or otherwise becoming detached from themargins of the cover sheets and falling out along the edges. Special"machines are required to produce this covered edge plaster board usingdifferent widths of paper and special mecha- Such nism for folding thewider sheet over the edge.

It IS an object of-this invention to produce a plaster board having anopen or raw edge that will possess the advantages trated on theaccompanying sheets of drawing and it is to be understood that minordetail changes may be made therein without departing from the scope ofthe invention.

Figure 1 is a view in perspective of this improved board. 1

FigureQ is a view in transversesection, with parts broken away, takenthrough this board.

I Figure 3 is a view of the machine partly in side elevation and partlyin longitudinal vertical section.

Figure 4 is a top plan view of Figure 3.

Figure 5 is a view similar to Figure 3, of a modified form of machine.

Figure 6 is a view similar to Figure 4, of said modified form ofmachine.

The production of an open or raw edged plaster board which possesses themore percovered edge plaster board is accomplished in accordance withthis invention by making the edges of the plastic mineral core or bodymuch stronger than the main body of the board and much tougher so thatit will stand more abuse on these edges without harm.

In carrying out this invention'the ordinary calclned gypsum, li htaggregate or fibre, and ,water are mlxe as usual except that before themixed plastic mass goes through the board forming mechanism, adetermined amount of the plastic mass is diverted from the main mass-ofthe mixture to the outside six to nine inches of the board alon eachedge and during this diversion and efore passing throu h the formingmechanism, this portion 0 the plastic mass is mixed with a colloidalgummy body that has the property of hardening and tougheninggypsumpiastic masses when set and dried out. The particular gummycolloidal matter may be added either as a dry powder to the plastic massat this stage or as a solution to the partially mixed and segregated o'rdiverted portions of the plastic core. By this means the core of theformed board is divided into three portions, the strip on each side ofhardened and toughened plaster and the intern'iediate portion of normalplaster, so that the edges will standmorc abuse than the main body ofthe untreated core and thus protection is produced in an economicalmanner for the expensive colloidal matter is applied only at the edgeswhere the protection is mostly needed.

Since it is customary in this art to man ufacture plaster wallboardcontinuously on a machine which advances a bottom cover.

sheet, depositing the material forming the body of the board in aplastic condition upon this sheet, applying a fibrous upper cover sheetupon the plastic body, with means for moulding-or retaining the plasticbody between the cover sheets at the edge, and then transporting theboard so formed upon a conveyor of sufficient-length to allow theplastic body to partially set, bond to the cover sheets and become hardenough 1 to allow of the cutting of the strip of board so formed inequal lengths, remove the cut portions from the end of the conveyor andtransport to'the drying kilns, it is only necessary to illustrate anddescribe the wet or board forming end of such a machine, as thisinvention relates only to the method and means of forming a particulartype of plaster wall board.

As shown in Figures 3 and 4, the machine for carrying out this inventioncom prises a flat table -1 over which a fibrous bot- 7 tom cover sheet'2is advanced from aroll 8 preferably supported below the table. As thisbottom sheetfadvances' along .the table the material- 4 forming the bodyof the board is deposited thereon in a'plastic state,

- preferably from a '.belt conveyor 5. The

fibrous top cover sheet 6 is applied over the surface of theplasticmass, from aroll 7 supported above the table preferably bypassing this sheet about the pressure or forming roll 8 This formingroll 8 is of same width 'as the finished board and is supported abovethe table in such a manner that it will impart the desired thickness tothe board formed by the passage of the plastic body between the twocover sheets thereunder. If desired, a corresponding pressure roll 9-maybe mounted on the table directly under-the upper forming roll -to co-acttherewith in forming the board. As the bottom cover sheet lies flat .onthe table throughout its width, and as the top cover sheet is appliedfiat throughout its width uponthe upper surface of the plastic -mass,means must be provided, to prevent the plastic body from overflowing theedges of the bottom cover sheet as it advances and carries the plasticbody toward the forming roll, also to retain the plastic body bc-- tweenthe two cover sheets after the board has been formed and until the bodyhas had time to set sufficiently to maintain the conformation of asquared edge. There are various means known in this art for maintainingor moulding the edges of plaster board constructed in this manner.- Inthis case, vertical belts 10 are Illustrated wlnch travel at thesamerate as the formed board along each edge of the bottom cover sheet asit. advances toward the forming roll and thereafter along each edge ofthe formed board which belts pass .over vertical pulleys arranged tomaintain the moult mg belts against the edges of the cover sheets andthereby prevent the body of the board while plastic from overflowing thecover sheet and oozing out at the edges of the formed board. v

Since fibrous cover sheets of the character employed in plasterwallboard' manufactating knives 11 just beforethe cover sheets .pass onto the table and forming roll respectively.

Since it is contemplated by t-his invention to treat the plastic mass insuch amanner that the edges 12 and 13 ofthe board will be harder andtougher than the intermediate body portion 14, it is necessary'to addand mix the necessary ingredients to the plastic body before it'passesthrough the board forming mechanism, and it therefore becomes necessaryto segregate the portions of the plastic masses which ultimately formthe edges of the finished board as the mass advances on the bottom coversheet toward theforming roll and'this is preferably accomplished byproviding 'angularly disposed dams or guide plates'15supported above thetable a suflicient distance to a1 low the bottom sheet to passthereunder and.

arranged so as toengage the outer portion of the plastic. mass when,first deposited upon the bottom sheetand deflect a portion from eachside as it advances toward the forming rollso that these portionswill beseparated from the intermediate body per-- tion'and comprise the edgesof the board when formed. 'The'se angularly disposed plates are clearlyillustrated-in Figures 3, 4,

5 and 6. The plastic body in machines of this character naturally damsup in front of the forming 'roll and it is customary to providetransversely reciprocating spreaders 16, as illustrated, which in thiscase will insure the distribution of the plastic mass at theintermediate portionof the board and insure its combining withtheadjacent portions of the segregated or deflected plastic masses at theedges of the board.

The ingredients employed for producing the toughened or hardened edgeportions of the body of the board are preferably sulphite cellulose,pitch, gum arabic, or gum tragacanth, or gum tragasole, or any slmilarcolloidal gummy body that has the property of hardening and tougheninggypsum plastic masses when set and dried out and as above stated may beemployed in either a dry powdered state or in solution. Figures 3 and 4illustrate one manner of applying these ingredients upon the conveyor onwhich the'plastic body is mixed before it is deposited upon the bottomcover sheet and from which it is seen that a hopper or receptacle 17 isprovided aboveeach side of the conveyor adapted. to discharge, thetoughening or hardening substance, in either powdered form or insolution, to the edges of the plastic mass on the conveyor, To insure aproper and uniform intefmin'gling between these ingredients and plasticbody, it is preferable tov provide mixmg discs, 18, or other devices,between the discharge openings of these hoppers and discharge end of theconveyor so that when the plastic mass is deposited upon the bottomsheet the outer edges will be thorou hly mixed with the ingredients andthe de eating plates are so arranged that after the mass 18 deposited onthe bottom sheet they will separate the mixed edge ortions from theintermediate body and de ect these mixed portions to. the edges oftheboard as it passes under the for roll.

If desiredthe ingredients may be added to the plastic mass after 'it hasbeen deposited on the bottom cover sheet, as illustrated in Figures 5and 6, by placing the discharge hop ers 17 above the table so as todischarget eir contents on the segregated ortions of the plastic massbetween the gui e plates and respective edges of the bottom sheet and inthis case, it is also preferable'to provide mixing devices 18 betweenthe hopper and fine forming roll to insure a 'frm' 11. 0 0 mgro properintermin hng of ingredients with the plastic bodyhiefore it passes underthe What I claim is :1. The method for producing plas'ter;

board having a composition body and upper and lower cover sheets,comprising the depositing of the bodyin a plastic mass upon the lowercover, sheet, applying the 'top tions of the edges of'the board beforethe application of the upper cover sheet with substances to harden andtoughen said edges when set.

2. The method for producing plaster board having a plaster body andupper and lower fibrous cover sheets comprislng the depositing of thebod in- -a plastic mass upon the lower cover s eet, incorporating a gummcolloid in the edges of the plastic mass orming the edges of the board,and applying the upper cover sheet.

3. The method forproducing' plastic board having a plaster body andupperan lower fibrous cover sheets com using the depositing of the bodyin a p astic mass upon the lower cover sheet, incorporating a substancein the edges of the plastic mass forming the edges of the board, andapply ortions of the plastic mass a gummy col-- oid,diver'ting saidportions to the edges of the board, and applying the upper cover sheetthereover.

5. The method for producing plaster board having a plaster body andupper and lower cover sheets, comprising the depositlhg of the body in aplastic mass upon the lower cover sheet, incorporating in the edgeportions of the plastic mass a substance,

iverting said ortions to the edges of the board, and app yi'ng the uppercover sheet thereover.

6. The method for reducing laster board havinga body wit upper an vlower fibrous cover sheets bonded to the flat sides thereof, complris n%,the advancing of the lower cover s eet, e ositing' the body in aplastic mass upon t e lower cover sheet, mixing a-gummy'colloid with theportions of-the plastic mass that. form the edges of the board to renderthe edges when set harder and tougher than the intermediate bodyportion, applying an upper cover sheet, and

passing the plastic-mass between thecover sheets through a board formingdevice.

7. The method for producing plaster board having a body wit 11 pier andlower cover sheets bonded to the of, comprising the advancing of thelower 'cover sheet, depositing the body in' a plastic mass thereon,incorporating a ummy colloid in the edges of the plastlc mass, d-iatsides there- V verting the portions with the incorporated additiontowards the edges of the; cover sheet, applying the upper cover sheet,and passing the plastic massbetween the cover sheets through a boardforming device.

8. A method for producing plasterboard -lower1 cover sheets,

.gredients that render the having a bod with upper and lower fibrousnded to the flat side's thereof, comprising theadvancing of the lowercover sheets cover sheet, depositing the body in a plastic mass thereon,incorporating a gumm colloidin the edges of the plastic mass,- vertingthe portions with the incorporated addition towards the edges of thecover sheet, a plying the upper cover sheet, passin the p astic massbetween the cover s eets through a board formin device, and retainingthe plastic body etween the cover sheets at the edges until the mass hasset.-

9. A machine for producing plaster board having a composition body withupper and comprising means for advancing the lower cover sheet, meansfor depositing the body in a plastic-mass upon the cover sheet as itadvances, means for applyin the top cover sheet over the lastic mass, aboard forming roll under whichthe plastic mass between the cover sheetspasses, and means'for incorporating in the plastic mass that forms theedges of the board before it passes beneath the forming roll ined s ofthe set oard harder and tougher tEZn the inter- "inediate portion of thebody.

10. A machine for producing plaster board havin a plaster body and coversheets on the fiat aces thereof comprising means for advancing a low 1-cover sheet, means for'de siting the pl ter body in a last'ic 'mass tereon as it corporatin a gummy colloid in the edge portions 0 theplastic mass, means forgaping an upper cover sheet therepver, and

advances, means or in-' masses a board formin means through which theplastic mass an cover sheets pass with the colloid incorporated portionsat the edges ofthe board. 11.- A plaster board forming machinecomprising means for advancing lower cover sheet, means for depositing a'plaster body rtion thereon in a plastic mass, means for epositing agummy colloid on portions of the plastic mass, mean'sfor mixing the.colloid therewith, means for diverting the said mixed portions to theedges of the cover sheet, means for a pl ing an upper cover sheetthereover, an a ard forming means through which the plastic mass andcover sheets ass. 1

12. plaster board forming machine comprising means for advancing a lowercover sheet, means for depositing the plaster body thereon in a plasticmass, means for applying the upper cover sheet thereover, means throughwhich the lastic mass and cover sheets pass to form t e board, meansarranged on each side of the cover sheets for retaining the plaster massupon the lower sheet as it advances and between the two sheets afterthey have passed the board forming means, means for depositing a gummycolloid upon portions of the plastic mass, means for-mining andincorporating the colloid with the plastic mass, and means above thelower cover sheet for diverting the portions with the mixed colloidtowards the ed es of the said sheet as it advances towar s the boardforming means.

HARRY n. BROOKBY.

